Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
INTEREST AND DIVIDEND INCOME
Loan receivable	$ 427,621	$ 390,440	$ 359,959
Investment securities- taxable	21,523	24,237	43,412
Investment securities- nontaxable			995
Federal Home Loan Bank stock	3,164	1,974	1,480
Deposits with banks	1,398	1,996	1,150
Total interest and dividend income	453,706	418,647	406,996
INTEREST EXPENSE
Time deposits	39,443	35,111	31,964
Other deposits	12,445	10,658	8,425
Interest on securities sold under agreements to repurchase	15,813	24,685	37,692
Advances from the Federal Home Loan Bank	487	945	528
Long-term debt	5,776	4,467	3,691
Total interest expense	73,964	75,866	82,300
Net interest income before provision for credit losses	379,742	342,781	324,696
Reversal for credit losses	(11,400)	(10,800)	(3,000)
Net interest income after provision for credit losses	391,142	353,581	327,696
NON-INTEREST INCOME
Securities (losses)/gains, net	(3,349)	6,748	27,362
Letters of credit commissions	5,545	6,043	6,281
Depository service fees	5,348	5,288	5,701
Other operating income	25,130	22,448	20,963
Total non-interest income	32,674	40,527	60,307
NON-INTEREST EXPENSE
Salaries and employee benefits	89,960	89,893	88,276
Occupancy expense	17,018	15,735	14,846
Computer and equipment expense	9,828	9,793	9,768
Professional services expense	25,014	22,634	24,574
FDIC and State assessments	9,087	8,796	7,351
Marketing expense	4,926	4,126	3,403
Other real estate owned income	(800)	(1,304)	(235)
Operations of investments in affordable housing and alternative energy partnerships, net	33,335	6,990	7,253
Amortization of core deposit premium	667	719	4,533
Cost associated with debt redemption		3,348	22,557
Other operating expense	13,685	13,583	11,507
Total non-interest expense	202,720	174,313	193,833
Income before income tax expense	221,096	219,795	194,170
Income tax expense	59,987	81,965	70,435
Net income	161,109	137,830	123,735
Less: net income attributable to noncontrolling interest			592
Net income attributable to Cathay General Bancorp	161,109	137,830	123,143
Dividends on preferred stock			(9,685)
Net income attributable to common stockholders	161,109	137,830	113,458
Other comprehensive (loss)/income, net of tax:
Unrealized holding (losses)/gains on securities available for sale	(4,200)	30,468	(14,335)
Unrealized holding losses on cash flow hedge derivatives	(598)	(2,397)
Less: reclassification adjustment for (losses)/gains included in net income	(1,941)	3,911	15,859
Total other comprehensive (loss)/income, net of tax	(2,857)	24,160	(30,194)
Total comprehensive income	$ 158,252	$ 161,990	$ 92,949
Net income attributable to common stockholders per common share
Basic (in Dollars per share)	$ 2.00	$ 1.73	$ 1.44
Diluted (in Dollars per share)	$ 1.98	$ 1.72	$ 1.43
Basic average common shares outstanding (in Shares)	80,563,577	79,661,571	78,954,898
Diluted average common shares outstanding (in Shares)	81,294,796	80,106,895	79,137,983